I think your ferm temps are a bit low, but (better low than high)
As far as not having a gusher, it happens! All of my brews up to this point have all required a blow off tube except for my last batch of holiday ale. Id be surprised if the krausen ring even made it to 1/2" above the brew. The fermentation bubbling of the airlock is steady at a few burps a minute, but in no way is this a gusher like I had figured it might be.
Beers are fickle - I rig off a blow off on EVERY brew, but sometimes the yeast dont feel like getting rowdy. I dont think its anything to worry about